ram: rk3399: Simplify data training first argument

ram: rk3399: Simplify data training first argument

data training is using chan_info as first argument with
channel number as second argument instead of that use
dram_info as first argument so-that we can get the
chan_info at data training definition.

This was the argument handling is meaningful, readable
and it would help to add similar data training for
lpddr4 in future.

Signed-off-by: Jagan Teki <jagan@amarulasolutions.com>
Reviewed-by: Kever Yang <Kever.yang@rock-chips.com>